Boron-tuned tetrahedral Co(II) sites in zeolite beta enhance propane dehydrogenation

Zeolite-embedded cobalt sites show great potential for propane dehydrogenation (PDH), with isolated tetrahedral Co(II) (Td-Co(II)) species that interact strongly with reactants and outperform many other non-noble metal catalysts. However, excessively strong interactions can raise the reaction energy barrier and hinder catalytic turnover. Incorporating heterometal atoms offers a strategy to moderate these interactions but often introduces additional active sites that promote undesired over-dissociation of propylene. Here we introduce p-block boron species as non-metallic heteroatoms and use dealuminated siliceous beta zeolite (SiBEA) as the support to fine-tune the reactivity of well-dispersed Td-Co(II) species, thereby overcoming the inherent activity–selectivity trade-off. While boron itself shows negligible propylene productivity, boron-modified Td-Co(II) catalysts achieve significantly improved initial propane conversion (27.9% to 46.6%) while maintaining high C 3 H 6 selectivity (~99%). This catalyst also maintains performance with no significant activity loss over multiple regeneration cycles. Spectroscopic and microscopic analyses reveal that well-dispersed Td-Co(II) species are anchored at the silanol nests of SiBEA, with structural distortion induced by their chelation with boron species. Mechanistic studies indicate that boron acts as an electron reservoir, modulating Co–intermediate interactions to suppress propylene over-dissociation while lowering the energy barrier for C–H activation. • Well-dispersed Td-Co(II) species anchor at SiBEA silanol nests and are distorted via boron coordination. • The boron modifier mitigates the activity–selectivity trade-off in Td-Co(II) sites for PDH. • Boron-tuned Td-Co(II) catalysts maintain high PDH activity over multiple regeneration cycles. • Acting as an electron reservoir, boron promotes C–H activation of C 3 H 8 and suppresses C 3 H 6 over-dissociation.